Medical Fluid Cassettes and Related Systems

ABSTRACT

The invention relates to an apparatus for the treatment of a medical liquid comprising a liquid treatment machine and a cassette insertable therein substantially made of a rigid base body of the cassette with fitted chambers and passages and a foil covering them.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of and claims priority toU.S. application Ser. No. 12/627,043, filed on Nov. 30, 2009, which is acontinuation application of and claims priority to U.S. application Ser.No. 10/516,528, filed on Dec. 2, 2004, which is a nationalization ofPCT/EP03/05377, filed on May 22, 2003 and published in German, whichclaims priority under 35 U.S.C. §119(a) to DE 102 24 750.1, filed onJun. 4, 2002.

TECHNICAL FIELD

The invention relates to an apparatus for the treatment of a medicalfluid comprising a fluid treatment machine and a cassette insertabletherein substantially consisting of a rigid base body of the cassettewith fitted chambers and passages and a foil covering them.

BACKGROUND

Cassettes are used in medical engineering, in particular to conveydialysis fluid, blood and the like.

A cassette can include a base body with fitted chambers and passageswhich is closed by a flexible foil to cover the passages and chambers.The cassette can be inserted into a special receiving chamber, e.g., ina dialysis machine. This chamber can, for example, be opened via apivotable door. The cassette can be inserted into the chamber, with theflexible foil lying opposite a corresponding mating piece at the machineso that the cassette can be operated with the aid of actuators andsensors on the machine side.

Conventional extracorporeal blood circuits or blood tubing systems areusually present in a differential construction. This means that afunctional division onto different components is present. Suchcomponents (e.g., bubble traps, flow chambers or injection positions)are connected to one another by tubes and are as a rule connectedindividually to the respective dialysis machine. The design of suchblood tubing systems is very complex in manufacture and handling, withthe corresponding effort naturally being extremely time consuming withmore complex systems such as an online hemodiafiltration.

On the other hand, conventional extracorporeal blood circuits which areinstalled in this differential construction have the advantage that theycan be designed substantially more flexibly for the respective treatmentdepending on the demand. Previously known apparatuses for the use ofcassettes typically were only usable for a very specific application.

SUMMARY

Certain aspects of the invention relate to a generic apparatuscomprising a fluid treatment machine and a cassette insertable thereinsuch that a large flexibility for different applications is madepossible while maintaining the fast and simple exchangeability.

In some aspects of the invention, actuators and sensors are arranged ina generic apparatus for the treatment of a medical fluid for theoperation of the apparatus with an inserted cassette such that cassettesare insertable in different integration shapes.

Due to the clearly defined arrangement of corresponding sensors andactuators, cassettes of different complexity can be inserted into thefluid treatment machine in accordance with the desired application. Itis therefore not necessary to provide different apparatus for differentapplications.

A cassette for a standard hemodialysis can thus be insertable here, forexample. The corresponding pump chambers, measuring sensors and furtheractuators, such as valves, etc., are provided at pre-determinedlocations in the fluid treatment machine. Additional pumps, actuators,valves, etc. are provided in the fluid treatment machine which do nothave to be actuated when the cassette is used for standard hemodialysis.They are, for example, only in use when a cassette is used for onlinehemodiafiltration or online hemofiltration. Further passages, pumpchambers, etc. are provided at corresponding positions in thecorresponding cassettes which are associated with these actuators, pumpsor valves. Furthermore, a cassette for an acute dialysis treatment canbe inserted in which in turn the pumps, actuators and valves provided onthe side of the fluid treatment machine are associated withcorresponding pumping chambers, passages, etc. The associated controlelectronics can be selected depending on the inserted cassette for thecontrol of the pumps, actuators, sensors, etc.

DESCRIPTION OF DRAWINGS

Details and advantages of the invention will be explained in more detailby way of example in the following with reference to the Figures. Thereare shown:

FIG. 1: a schematic plan view of a cassette for standard hemodialysis;

FIG. 2: a schematic plan view of a cassette in accordance with theinvention according to a further embodiment of the invention for use inonline hemodiafiltration or online hemofiltration;

FIG. 3: a plan view of a cassette in accordance with a furtherembodiment of the present invention which can be used for acutetreatment;

FIG. 4: a schematic plan view of a further aspect of the invention whichsubstantially corresponds to that in accordance with FIG. 1, but has anintegrated dialyzer;

FIG. 5: a further aspect of the invention which substantiallycorresponds to that in accordance with FIG. 2, but has an integrateddialyzer;

FIG. 6: a further embodiment of the invention which substantiallycorresponds to that in accordance with FIG. 3, but has an integrateddialyzer;

FIG. 7: a three-dimensional representation of a fluid treatment machineas an embodiment of the apparatus in accordance with the inventionwithout an inserted cassette;

FIG. 8: a representation corresponding to FIG. 7, but with an insertedcassette;

FIG. 9: a representation in accordance with FIG. 7, but with a differentembodiment variant of a cassette differing from the cassette shown inFIG. 8;

FIG. 10: a detail of a venting unit in the apparatus in accordance withthe invention;

FIG. 11: a detailed view of a contour of a measuring chamber in acassette in accordance with one of the aforesaid embodiment variants;

FIG. 12: a partially sectional representation of a pump chamber of thecassette in accordance with the present invention;

FIG. 13: a partially sectional representation through a passage of thecassette in accordance with an embodiment variant of the invention;

FIG. 14: a cross-sectional view of a valve;

FIG. 15: a diagrammatic view of the valve of FIG. 14 in use in adisposable cartridge;

FIG. 16: a perspective view of a fluid guide body having an open mainpassage and a secondary passage opening therein in accordance with anembodiment of the invention in a sectional representation;

FIG. 17: a perspective view of a base body of the cassette of FIG. 1 ina partial section, wherein a covering film is pressed onto the fluidguide body by a valve actuator and closes the secondary passage;

FIG. 18: a perspective view similar to FIG. 17, wherein the secondarypassage is represented in its open position; and

FIG. 19: a schematic, 3D representation of a section of an elastic mattaccording to an embodiment of the present invention;

FIG. 20: a section along the section line A-A′ in FIG. 19;

FIG. 21: a section along the section line B-B′ in FIG. 19;

FIG. 22: a section along the section line C-C′ in FIG. 19.

DETAILED DESCRIPTION

In FIG. 1, a cassette 10 in accordance with an embodiment of the presentinvention is shown which can be used for standard hemodialysis. In FIG.1, the surface of the cassette 10 is divided into a hatched region B(two partial areas) and a non-hatched region A. Both the surface of thecassette 10 and the surface of an associated machine block 108 (shown inFIG. 7) are divided into the covering surface regions A and B.Components of actuators or sensors to be coupled, which are common toall cassettes as basic variants (e.g., all the cassettes for standardhemodialysis) are accommodated in the surface region A (not hatched inFIG. 1), and the surface region B denotes a region in which actuators orsensors to be used optionally are provided in the machine block 108(shown in FIG. 7). As discussed below, FIG. 2 illustrates a cassettethat includes operable components in a region corresponding to a surfaceregion B.

The cassette consists of a base body 12 of a cassette which consists ofpolypropylene in the embodiment shown here. A cover foil 14 (shown inFIGS. 10, 12, 13, 17, and 18) consisting, for example, of a polyolefinelastomer mixture, is applied to the base body 12 of the cassette 10.The passages and recesses, which will be looked at in more detail later,are covered by this cover foil 14. An arterial injection septum 16 isprovided in the arterial line 18 to the dialyzer and a venous injectionseptum 20 is provided in the venous line 22 to the dialyzer. Thedialyzer itself and the corresponding tube connection are not shown inany more detail in the embodiment shown here. Reference number 24designates the blood inlet from the patient and reference number 26designates the blood outlet to the patient. The respective tubes, whichlikewise consist of a polyolefin elastomer mixture, are also not shownhere for reasons of simplification. Passages 28 are recessed in the basebody 12 of the cassette 10. They are acted on by a row of valves 30.

These valves 30 have a valve body with a pressure passage and a sealingcap which cooperates with the valve body such that it closes the end ofthe pressure passage on the valve body side with respect to theenvironment, with a pressure space being able to be built up between thepressure passage and the sealing cap so that the sealing cap has adeformable sealing region for entry into the fluid passage in order toclose this as required.

FIG. 14 shows one of the valves 30 in a sectional view, which isrotation-symmetric about a vertical axis. The valve 30 includes a valvebody 112 with a pressure channel 114, which ends in a pressure chamber116. A sealing cap 118 with a deformable area 120, which bounds thepressure chamber 116, is placed over the valve body 112.

The pressure channel 114 of the valve body 112 is elongated, so that itcan be inserted, for example, through the body or a wall of acounterpart of the disposable cassette 10 on the device side (i.e.,through the machine block 108) and can be screwed down with a lock nut122. A thread is provided on the outer wall of the portion of the valvebody 112 that forms the pressure channel 114 to allow the lock nut 122to secure the valve body 112 to the machine block 108. The valve body112 has sealing surfaces 124 for sealing the valve body 112 in themachine block 108. The sealing cap 118 includes protruding bulges 126,which surround the valve body 112 in such a way that they lie adjacentto the sealing surfaces 124 and are pressed when the valve 30 isassembled.

Still referring to FIG. 14, the upper area of the valve 30 is the areaon the fluid passage side (i.e., the side nearest the cassette 10). Aprojection 130 of the sealing cap 118 lies on the end of the valve body112, on the fluid passage side. A shoulder 128 of the sealing cap 118 isprovided to ensure that that the sealing cap 118 fits into itsassociated fluid passage in the cassette 10.

The valve 30 is shown diagramatically in use in FIG. 15. The base body12 of the disposable cassette 10 in which liquid passages 28 are formedis shown in diagrammatic representation. The corresponding counterpartof the disposable cartridge body on the device side (i.e., the machineblock 108) is shown pressed against the cassette 10.

The valve 30 is inserted into a suitably shaped housing (e.g., recess)138 of the machine block 108 and screwed down with the lock nut 122. Theshoulder 128 lies adjacent to the edges of the liquid passage 28. Themovement of the deformable area 120 when an excess pressure or partialvacuum is applied or with venting of the pressure channel 114 isindicated by arrow 140. Reference number 142 indicates the direction inwhich the pressure is applied in order to close the valve 30. As shownin FIG. 15, the housing 138 in the machine block 108 isrotation-symmetric about the pressure channel 114 of the valve 30, andthe liquid passage 28 extends perpendicular to the plane of the figure.

A cut-out for accommodating the shoulder 128 can be provided either inthe base body 12 of the cassette 10 or in the machine block 108. It isalso possible for the shoulder 128 to be accommodated in a suitableopening in a cover mat located between the cassette 10 and the machineblock 108.

For the sake of clarity, FIG. 15 does not show the cover foil 14 of thecassette 10, which closes off the fluid passage 28 against thesurroundings. The cover foil 14 (shown in FIGS. 10, 12, 13, 17, and 18)can be fixed on the side of the base body 12 of the cassette 10 that ispressed against the machine block 108. The cover foil 14 is sufficientlyflexible so that it can follow the deformation of the deformable area120 of the sealing cap 118 of the valve 130.

For the operation of the valve 30 with the cassette 10, the valve body112 is inserted through the housing 138 of the machine block 108, sothat the pressure channel 114 extends through the machine block 108. Thelock nut 122 is tightened up so that the protruding bulges 126 create aseal between the valve body 112 and the machine block 108. By simplyscrewing the lock nut 122 onto the valve body 112, a tight and reliableconnection of the valve 30 with the machine block 108 is thus provided.

The machine block 108 with the valve 30 is pressed against the cassette10, whereby the shoulders 128 of the sealing cap 118 fit tightly withthe edges of the liquid passage 28. By pressing the machine block 108against the disposable cassette 10, several valves 30 can besimultaneously fitted into their corresponding liquid passages 28 at thedesired points.

The dialysis liquid, for example, flows through the fluid passage 28when the valve 30 is in the opened state. If excess pressure is appliedvia the pressure channel 114 in the direction of the arrow 142, thedeformable area 120 of the sealing cap 118 is deformed into the liquidpassage 28 until the valve 30 is finally closed. The loading on thesealing cap 118 is reduced by the projection 130 of the sealing cap 118,without the movement of the deformable area 120 being significantlyimpaired. The cover foil 14 of the cassette 10 is deformed together withthe sealing cap 118 into the liquid passage 28.

If the fluid passage 28 is to be opened again, the pressure channel 114is vented and the deformable area 120 of the sealing cap 118 is relaxed.By applying a partial vacuum to the pressure channel 114, the deformablearea 120 is placed against the convex curvature of the pressure chamber116 and correspondingly increases the cross-section of the fluid passage28. By simply applying or removing a pressurization to the pressurechannel 114, therefore, the flow rate through the fluid passage 28 canbe controlled.

When the disposable cartridge is removed, the valve 30 can be removed orreplaced simply by loosening lock nut 122, e.g., for maintenance or inthe event of malfunction.

The sealing cap 118 is a simple low-cost shaped part, which on accountof its closed design can easily be cleaned and thus satisfies thehygiene requirements in dialysis, but which can also easily be replacedwhen necessary.

When the disposable cassette 10 is again compressed between the machineblock 108 and the base body 12, the valve 30 fits into the fluid passage28 very well by pressing the shoulder 128 with the edge of the fluidpassage 28. On account of the elastic stretching of the deformable area120 of the sealing cap 118, there is a very good tolerance compensationboth in the depth of the fluid passage 28 as well as in respect oflateral misalignment, without a significant additional expenditure offorce. The deformable area 120 guarantees that only small forces arerequired to block the fluid passage 28.

Other details regarding the valves 30 and their operation withdisposable cartridges, such as the cassette 10 described above, arediscussed in DE 100 46 651, which is incorporated by reference herein.

Referring again to FIG. 1, an arterial measuring chamber 32 and a venousmeasuring chamber 34 are furthermore recessed in the base body 12 of thecassette 10. The basic design of these measuring chambers is shown inFIG. 11. Referring to FIG. 11, the flow direction of the fluid, i.e., ofthe blood through the chambers 32, 34, is indicated by the arrows. Themeasuring chambers 32 and 34 have a widened passage section to be ableto receive the sensors 36. The contour of the measuring chambers 32, 34corresponds to a diffuser nozzle geometry such as is shown in FIG. 11. Adiffuser 38, which runs out in a nozzle 40, is arranged in the region ofthe inflow region of the fluid. The widened cross-section in thediffuser 38 is relatively rapid in comparison to the narrowedcross-section in the nozzle 40. The sensors 36, which are made in theform of multi-functional sensors, are arranged in the region of thearterial or venous measuring chamber 32, 34.

More specifically, each of the sensors 36 for measuring selectedparameters of the medical fluid passing in the arterial and venousmeasuring chambers 32, 34 is disposed on a measurement plate that has aperipheral seal along its outer edge and that is in contact with theflexible membrane (i.e., the foil 14). The measurement plate has aninlet that leads to the foil 14 so that a vacuum can be establishedbetween the measurement plate and the foil 14.

Several sensors can be mounted on the measurement plate, and since theflexible membrane (i.e., the foil 14) can be brought in close contactwith the measurement plate, the medical fluids are separated from thesensors on the measurement plate only by the foil 14. Because of theperipheral seal disposed on the measurement plate, the foil 14 can bebrought in close contact with the underside of the measurement plate byapplying a vacuum, so that very close contact can be established betweenthe sensors and the medical fluid in the measurement chamber. Thecontact surface of at least one of the sensors is preferably flush withthe underside of the measurement plate, so that it is possible toestablish direct measurement contact between the respective sensor andthe flexible membrane.

Because of advances in miniaturization and integration technology ofsensors, it is possible to arrange multiple sensors on an area a fewsquare centimeters in size. Each respective sensor is preferably mountedin a recess in the measurement plate, with the measurement surface ofthe sensor being in flush contact with the underside of the measurementplate. The sensors are preferably securely glued to the measurementplate.

For example, a pressure sensor and a temperature sensor may be used.Pressure sensors have become available formed on individualsemiconductor chips due to advances in integration of Microsystems, sothat the chips carrying the sensor are only a few square millimeters insize. Because the sensor surface can be brought in direct contact withthe foil 14, it is possible to measure both positive and negativepressures. As a result, the thermal energy balance and the venouspressure in a dialysis machine can be measured with the pressure sensorand the temperature sensor.

In some implementations, the seal of the measurement plate is made of arubber ring which is inserted into a groove in the measurement plate andprojects slightly above the edge of the measurement plate. As soon as avacuum is established between the membrane (i.e., the foil 14) and themeasurement plate, the foil 14 is pressed tightly against the undersideof the measurement plate by the ambient air pressure, and the sealguarantees that no additional air can flow into the area between themeasurement plate and the foil 14.

The measurement plate can be made of a metal disk into which therespective sensors are inserted. In some implementations, the metal diskis kept at a constant temperature by, for example, Peltier elements.This design permits a more accurate temperature measurement of themedical fluid.

Before performing the individual measurements, a vacuum is first appliedto the inlet so that the film (i.e., the foil 14) is placed in closecontact with the sensors. Then, the sensors are activated by a controlunit (not shown), so that the respective measurements can begin.

The above-described sensor arrangement is described in greater detail inDE 198 37 667, which is incorporated by reference herein.

Referring again to FIG. 1, an arterial port 42 and a heparin port 44 areprovided at the cassette, which are each connected via correspondingpassages to the passage carrying the arterial blood in each case viaphantom valves 46. The phantom valves 46 are used in the cassette 10 inaccordance with the invention instead of conventional open T-branches.In these phantom valves, the passage wall is not interrupted from theaspect of the main blood flow. Reference number 48 designates a venousport which likewise opens into a blood-carrying passage 28, here in thevenous part of the blood-carrying passages, via a phantom valve 46.

As FIG. 16 shows, and as discussed above, the fluid guide body (i.e.,the base body 12) of the cassette 10 has a main fluid passage 28, whichis integrally worked into the base body 12 and is closed by a coveringfilm (i.e., the foil 14), which is not shown in FIG. 16.

The fluid guide body (i.e., the base body 12) further has a secondarypassage 144 that leads away from the rear side of the base body 12,which is remote from the open side of the main passage 28, onto theopposite front side of the base body 12 and opens there into the mainpassage 28. As FIG. 17 shows, the secondary passage 144 passes through abase 146 of the main passage 28. The secondary passage 144 extends intothe main passage 28 in the form of a volcano-like funnel 148 whoseheight corresponds to the depth of the main passage 28 so that anorifice 150 of the secondary passage 144 is arranged verticallycoincident with the rims of the main passage 28.

The secondary passage 144 is positioned symmetrically in the center ofthe main passage 28 and extends perpendicularly to the longitudinaldirection of the main passage 28. The planar designed orifice 150 is inthe plane which is set up by the rims of the main passage 28.

As FIG. 16 shows, the funnel 148 has a streamlined cross-section. Inmore precise terms, the outside of the wall of the secondary passage 144in the main passage 28 is formed in streamlined manner, with thelongitudinal axis of the streamlined shape corresponding to thelongitudinal axis of the main passage 28. Vortexes, turbulences and anincreased flow resistance are thereby avoided at the secondary passage144. The medical fluid flowing through the main passage 28 can flow pastthe secondary passage 144 in laminar fashion.

As FIG. 16 shows, the contours of the main passage 28 are also formedextending in streamlined fashion around the secondary passage 144. Theside walls of the main passage 28 opposite the funnel 148 bulge instreamlined fashion around the funnel 148 so that the fluid flow forkingaround the funnel 148 finds approximately the same flow cross-sectionand can flow past the funnel 148 without speed changes.

To be able to close the open side of the secondary passage 144 andsimultaneously the orifice 150 of the secondary passage 144, thecovering film (i.e., the foil 14), which can be welded or connected inanother way to the base body 12, lies on the base body 12. To seal themain passage 28, the foil 14 can be welded to the base body 12 along therims of the main passage 28. The sealing can, however, also be effectedby pressing the foil 14 along the rims of the main passage 28 by a valveplunger 152.

The valve plunger 152 has a continuous, planar plunger surface 154 thatis formed by an elastic (e.g., elastomer) machine membrane. Due to thevertically coincident arrangement of the orifice 150 with the rims ofthe main passage 28, the secondary passage 144 can be closed withoutstretching of the foil 14, if the foil 14 is pressed onto the base body12. The orifice 150 is formed for this purpose as a planar valve seat156, which is in the plane set up by the rims of the main passage 28 andforms the front end of the funnel 148.

FIG. 17 shows the closed state of the secondary passage 144. The plungersurface 154 is pressed onto the base body 12. Additional pressure can beapplied by an actuating part 158 in the region of the orifice 150 of thesecondary passage 144 in order to achieve a reliable sealing of thesecondary passage 144.

To open the secondary passage 144, the actuating part 158, which isconnected to the plunger surface 154 in the region of the secondarypassage orifice 150, is moved away from the base body 12. The plungersurface 154 is thereby raised from the orifice 150 of the secondarypassage 144 in the region thereof. As FIG. 18 shows, the plunger surface154 thereby deforms, which is allowed by the design of the same as anelastic membrane.

The foil 14 also lifts off the orifice 150 of the secondary passage 144due to the raising of the plunger surface 154. The pressure of the flowin the main passage 28 presses the foil 14 away from the orifice 150.Optionally, this can also be supported actively by the interposition ofa vacuum between the plunger surface 154 and the foil 14, which ishelpful in particular when a sample should be sucked from the fluid flowin the main passage 28 through the secondary passage 144.

When the actuating part 158 lifts, the foil 14 stretches elastically.The deformation is here very low, however. It is in particular notplastic so that a formation of creases in the subsequent re-closing ofthe orifice 150 is prevented. As FIG. 18 shows, the secondary passage144 is in flow communication with the main passage 28 in the raisedstate of the foil 14.

Other details regarding the phantom valves 46 are described in DE 100 53441, which is incorporated by reference herein.

Referring again to FIG. 1, reference numbers 50 designate two pumpchambers which serve to pump the blood. The design of the pump chambers50 is shown in detail in FIG. 12. The pump chambers 50, which areactivated via membrane pumps provided at the machine side (i.e., in themachine block 108), have substantially tangential inlets and outlets fora uniform throughflow of the total chamber, as shown in FIG. 1. Theshape of the pump chambers 50 is pre-determined by the correspondinglyshaped base body 12 of the cassette 10 and can be approximatelydescribed as a spherical section. At the periphery, the base body 12 ofthe cassette 10 has a raised edge 52 around the pumping chambers 50which serves as a stop bead. In addition, as shown in FIG. 12, theperipheral edge of the spherical section is set somewhat lower so thatin the pressing-out phase, that is in the phase in which the cover foil14 is moved toward the base body 12 of the cassette 10, a flushing edgeor flushing passage 54 is formed. The flushing edge or flushing passage54 is advantageously made in that the spherical pump surface at themachine side (i.e., the spherical pump surface in the machine block108), which is not shown in FIG. 12, has a smaller radius than theradius of the pump chamber 50 at the cassette side. The radiusdifference Δ_(r) is shown in FIG. 12. A wide flushing edge or flushingpassage 54 is hereby formed. This flushing edge or flushing passage 54is an annular space for the pumped blood in the extreme pressing-outposition. This free annular space, on the one hand, avoids blood damageby being trapped between the foil surface and the injection moldedsurface (i.e., the base body 12) at the end of the pressing-out phaseand, on the other hand, blood damage due to high flow speeds andshearing strains which would result at the start of the start-up phaseif no free annular space were provided.

In the upper region of the cassette in the installed state, a ventingchamber 56 is formed which is shown again in FIG. 10 in a sectionalrepresentation. A venting membrane 58 is arranged in this ventingchamber via which correspondingly collected air can be separated sinceit is made as a partially permeable membrane which preferably hashydrophobic or oleophobic properties. Expanded or sinteredpolytetrafluoroethylene can preferably be used as the venting membrane.A venting stub 60 is arranged above the venting membrane 58 and itscooperation with the fluid treatment machine (not shown in more detailhere) will be described later.

Bubbles are trapped in the venting chamber 56 by a slowing down of theblood flow. As shown in FIG. 10, a rotation flow is generated foreffective air separation with minimum area requirements on the cassette10. In this process, the generation of the final rotation flow is onlycreated in the operating state of the cassette 10 in the fluid treatmentmachine 100. The cover foil 14 of the cassette 10 is pulled into thefluid treatment machine 100 by a corresponding vacuum coupling system ofwhich only one vacuum suction passage 102 is shown in FIG. 10. An almostcircular cross-section of the venting chamber 56 is thereby formed. Therotation flow of the blood is supported in that the passage opening intothe venting chamber 56 also runs—together with its cover foil14—slightly into the machine side so that an almost tangential inflowwithin the chamber is achieved. An effective suction can take place atthe machine side at the venting stub 60. A low filling volume resultsoverall here in the venting chamber 56 as a result of the construction.

The basic design of the passages 28 can be explained with reference toFIG. 13. Generally, care is taken in the passage design of the passages28 that a smooth foil surface and smooth passage surfaces are provided.Steps, dead spaces, turbulence and impact surfaces are avoided. Lowchanges in direction and speed are aimed for. Separations of flow arelargely avoided. All passages 28 and also chambers 50 have an edge bead52 which accompanies the passages and faces the cover foil 14. Oninsertion of the cassette 10 into the fluid treatment machine 100, thefoil 14 is pressed onto the edge bead 52 such that all passages 28 aresealed against the environment. At the rear of the cassette, i.e., atthe outer side of the passage wall, webs 62 are formed which accompanythe passages and via which the rear pressing force is guided to the edgebeads 52 in order thus to achieve a uniform linear distribution offorce.

It can also be explained with reference to FIG. 13 that the base body 12of the cassette 10 is welded to the cover foil 14 at the outer edge 64.

As shown in FIG. 1, the cassette 10 has a recessed centering fork 66 asa positioning aid which receives a centering pin on the machine side oninsertion. Stop noses 68 are furthermore molded on which contact againstcorresponding machine surfaces on insertion. The cassette 10 is therebyguided in height and angle. When pressing the cassette 10 into the fluidtreatment machine 100, a latching with the fluid treatment machine takesplace at a snap element not shown in more detail here such that thecassette 10 is fixed in an aligned manner. The cassette 10 has a moldedhandle 70 at the side disposed opposite the centering fork 66 forsimplified handling.

The arterial injection septum 16 or the venous injection septum 20 aremade in the embodiment shown here, in contrast to a conventionalinjection position, such that their base body is formed by the base body12 of the cassette itself so that here only the elastic septum is fixedby a snap ring (not shown in detail here). The septum consists of anelastomer in the embodiment shown here.

FIG. 4 shows a modified embodiment of the cassette in accordance withFIG. 1. This cassette 10 shown in FIG. 4 also serves standardhemodialysis and largely shows an identical design to the cassette 10 inaccordance with FIG. 1. To this extent, a detailed description of thealready described components of the cassette 10 is superfluous. However,instead of the handle 70 in the embodiment in accordance with FIG. 1, adialyzer 72 is integrated in the side of the cassette 10, with the lines18 and 22 to the dialyzer opening directly into the dialyzer. Thedialysate connections at the dialyzer, which can have a conventionaldesign, are designated by 74 and 76.

A cassette 10 is shown in FIG. 2 which is designed as an onlinehemodiafiltration cassette. It becomes clear from the arrangement of thedifferent elements that the base body 12 of the cassette 10 starts fromthat base body of a cassette such as has already been described in FIG.1 with reference to the embodiment for standard hemodialysis. Allelements which are known from this configuration can be found in thesame manner in the embodiment variant in accordance with FIG. 2 foronline hemodiafiltration. To this extent, they will not be additionallyexplained again. However, those parts will be explained which arenecessary for the operation of the hemodiafiltration cassette. Thisincludes the substituate connector 80 via which the substituate fluid isfed into the passages 28. Substituate passage valves 82 are provided atthe passages and the passages 28 can be closed at the appropriatepositions via these valves 82. The substituate fluid is guided into twoparallel pump chambers 84, which form substituate pump chambers, via thepassages 28. The substituate pump chambers 84 substantially correspondto the pump chambers for the blood 50 as they have previously alreadybeen described in detail. Starting from the passage 28, the substituatefluid is guided through a substituate tunnel 86 which is disposed on theopposite side of the base body 12 of the cassette 10. The substituatetunnel 26 is suitably closed at the rear side, e.g., by a welded foil.The substituate fluid 86 can be led into the passage 28 carrying theblood via a port for pre-dilution 88 or via a port for post-dilution 90.The ports are again made as phantom valves of the type described above.

The substituate region substantially formed by the substituate pumpchambers 84 is surrounded by a substituate weld rim 92 to which thecover foil 14 is sealingly welded so that this region of the cassette 10processing substituate is separated from the blood-carrying region.

In FIG. 5, a modification of the embodiment variant in accordance withFIG. 2 is shown. Here, too, in a similar manner to the embodimentvariant in accordance with FIG. 4, a dialyzer 72 is integrated directlyinto the cassette 10.

In FIG. 3, a cassette 10 for acute treatment is shown as a furtherintegrated embodiment of the cassette. It is designed identically to theembodiment variant in accordance with FIG. 1 in the region of the bloodtreatment part. With respect to the substituate part, it partlycorresponds to the embodiment in accordance with FIG. 2, with here onlyone substituate pump chamber 84 being provided which is fed by thesubstituate fluid led in via the substituate connector 80 and thepassage 28. In a similar manner as to the embodiment variant inaccordance with FIG. 2, substituate passage valves 82 are providedbefore and after the substituate pump chamber 84. The further pumpchamber, which is designated by 94 in the present embodiment variant foracute treatment, is connected to a filtrate outlet 96 via a passage 28and opens into a filtrate connection 98 which is connected to thedialyzer not shown in any more detail here.

In FIG. 6, in turn, a modified embodiment variant of the cassette 10 inaccordance with FIG. 3 is shown. Here, a dialyzer 72 is in turnintegrated instead of the handle, with here a connection 99 beingprovided between the dialyzer 72 and the passage 28 which carries thefiltrate and which leads to the filtrate pump chamber 94.

In FIG. 7, an embodiment of the fluid treatment machine 100 is shownwithout an inserted cassette 10. This fluid treatment machine 100 isdesigned such that all aforesaid cassettes can be inserted, with a basicextracorporeal blood circuit, i.e. a standard dialysis using an externaldialyzer, being carried out by a corresponding program selection, forexample on insertion of the cassette in accordance with the embodimentvariant in accordance with FIG. 1. When a cassette 10 in accordance withthe embodiment of FIG. 2 is used, online hemodiafiltration or an onlinehemofiltration variant is, for example realized by use of the componentsrequired for this purpose with, optionally, automatic connections (notshown) to the fluid circuit of the basic unit. Highly integratedvariants with an integrated dialyzer and an automatic dialyzerconnection are also possible such as are shown by way of the cassette inthe embodiment variants in accordance with FIGS. 4 and 5. Acute dialysistreatment is possible when a cassette 10 is used in accordance with theembodiment of FIG. 3.

The fluid treatment machine 100 substantially consists of a frame 104which surrounds and/or includes or receives the most importantcomponents. A door 106 is fitted to the frame 104, on the one hand, andthe machine block 108 is guided in the frame, on the other hand. Allforces occurring between the door 106 and the interior of the unit areabsorbed by means of the frame 104, namely the door hinge, door latch,pressing actuator system and the rear wall. The frame 104 furthermorecontains the door latch 110. The cassette 10 is received between thedoor 106 and the machine block 108, as shown in the FIGS. 8 and 9, andis sealed by pressing. Sensor system elements are included in thecassette region of the machine and they detect whether a cassette iscorrectly positioned in the fluid treatment machine. These, or furthersensor system elements, can be designed such that they are suitable forrecognizing the cassette type (e.g. with the aid of a barcode on thecassette).

The important elements for the control and monitoring of theextracorporeal blood circuit, such as pumps, valves, the sensor system,etc., are contained in the machine block 108. This machine block 108establishes the most important interface to the cassette 10. Thecassette surface is coupled to the unit here and the sealing of thecassette 10, and thus the fixing of the flow paths, takes place by this.The machine block 108 is guided movably in the frame and fixes thecassette 10, as already described above, until the door 106 is closed.

Hydraulic piston pumps are contained in the fluid treatment machinewhich are not shown in detail in FIGS. 7, 8 and 9 here. They are, on theone hand, blood pumps or optional substituate feed pumps orultrafiltrate pumps. They are hydraulically connected to the pumpchambers (i.e., the blood pump chambers) C, D, and, in some cases, theyare hydraulically connected to the optional filtrate pump chambersand/or the optional substituate pump chambers E, F. Furthermore,compressors for the generation of the required pneumatic pressure(overpressure or vacuum) not shown in more detail here are contained inthe fluid treatment machine 100. The fluid treatment machine 100furthermore has—in a manner not shown in more detail—a pneumatic buffercontainer for the compensation of pressure fluctuations, a mainelectronics box, a heparin injection pump and a blood pressure monitormodule.

A pressing actuator system on the rear wall of the frame 104, likewisenot shown in more detail, must be emphasized here. An inflatable aircushion is integrated here which can move the whole machine block 108,which is movably supported in the frame 104, and press it against theclosed door 106.

Furthermore, instead of individual air-carrying tubes, an airdistributor plate is provided at the machine block 108 which containsmain connections for the pneumatics and which guides compressed air andvacuum to the valves and actuators via passages integrated there withoutany substantial tubing, with them simultaneously terminating the machineblock with respect to the interior of the fluid treatment machine 100.

Optional modules can be provided in the fluid treatment machine 100 forthe carrying out of the online hemodiafiltration. For instance, anonline feed port for the automatic coupling of a cassette 10 to adialysate circuit or an online flushing port for the return of flushingsolution can be contained here.

The door 106 must be open for the insertion of the cassette 10. Thecassette 10 is inserted and, after positioning of the centering fork 66,is fixed to the surface of the machine block by means of a snap hook.

The side of the machine block 108 facing the cassette 10 is lined with asoft elastomer mat 160 (shown in FIG. 19), which seals the cassette 10after pressing has taken place.

Referring to FIG. 19, during use, the elastic matt 160 is arrangedbetween the fluid treatment machine (i.e., the machine block 108), ofwhich no detail is shown here, and the cassette 10. On the so-calledmachine side, namely on the surface which, when assembled, faces thefluid treatment machine 100, matt channels 162 and connection channels164 are formed. Furthermore, a recess 166 is arranged in the elasticmatt 160, into which in the assembled condition a machine-mounted valve,for example, engages and establishes a seal all around. It is easy tosee that this machine-mounted valve interrupts the respective mattchannel 162 which happens to join the recess 166. In order to still makean air extraction possible, a connection channel 164 has been providedwhich connects the two interrupted branches of the matt channel 162 andconnects them in turn with a further, parallel matt channel 162. Thestructure shown here is, of course, only an example and can be changedin any way. While the channel structures are provided on the machineside of the elastic matt 160, the disposable side, namely the sidefacing the cassette, is executed as a smooth, i.e., flat surface.

By referring to the sectional views of FIGS. 20 to 22, the structure ofthe individual channels can be explained in more detail. The sectionA-A′ as per FIG. 19 is shown in FIG. 20 where a matt channel 162 becomesvisible which, with the elastic matt 160 used here having a thickness of4 mm, has a depth of 3 mm and a width of 2 mm. In the remaining mattmaterial below the channel 162, which has a thickness of 1 mm, a slit168 is placed which takes on a type of valve function. When a vacuum isapplied, the two areas of the elastic matt 160 adjacent to the slit 168will open and enable the extraction of air gas. In an idle state or whenan equilibrium is obtained, the two adjacent areas return to theiroriginal position and close the opening. In order to enhance this returneffect, areas between the slits 168 are provided in the matt channel162, which on the one hand do not have a slit and, on the other hand,are less deeply recessed in the area of matt channel 162. Referring toFIG. 21, a corresponding area can be seen in section B-B′, which showsthat, while the matt channel 162 in this area has the same width of 2mm, it only has a depth of 1 mm.

Referring to FIG. 22, a connection channel 164 is shown in the sectionalview of C-C′, where said channel is narrower and not as deep as the mattchannel 162, which can be seen clearly in this view. In this case, boththe width of the connection channel 164 and the depth are one millimetereach.

With the elastic matt 160, it is guaranteed that the interior space ofthe fluid treatment machine, in its idle state, is protected by theself-closing feature of slits 168. At the same time, an even airextraction is achieved between the fluid treatment machine and thecassette across its entire surface because parallel extraction takesplace via numerous slits 168. Thus, a minor blockage may not cause anydetrimental effects for other areas.

With a thin matt 160, as it has been presented in the embodiment forexample, the opening effect of the slits can be utilized by applying avacuum.

Since the elastic matt 160 is exchangeable, it can be replaced easilyafter contamination or a fault. It is especially advantageous that nostructured shapes are required for the fixed components on the machine.On the side of the elastic matt 160 facing the machine, open structurescan be formed so that no sub-surface tunnels or other closed structuresare required. On the other hand, the side of the elastic matt 160 facingthe cassette is largely formed as a smooth, closed surface which can becleaned easily for example.

Other details regarding the elastic matt 160 are described in DE 101 57924.1, which is incorporated by reference herein.

Referring again to FIG. 7, after closing and locking the door 106,pressing takes place by inflating the aforesaid air cushion. On openingand removing the cassette 10, the pressing is cancelled again by lettingout the air in the air cushion before opening the door 106.

To achieve a sufficient pressing and to prevent a tilting of the machineblock 108 by a non-uniform introduction of force, the air cushion hasapproximately the size of the machine block 108 or of the cassette 10.

Since, however, further components, for example, control valves or theair distributor plate with the control valves, are now disposed betweenthe air cushion and the machine block, the force transmission takesplace by means of spacer bolts.

The traction between the door 106, the frame 104 and the rear wall takesplace by the door hinge, the latch 110 and connection bolts, not shownin any more detail here, between the frame and the rear wall.

As already mentioned, a constant pressing of the cassette 10 must takeplace for a proper operation. For this purpose, it is necessary for thedoor 106 to be locked during the treatment. This locking takes place viatwo latching bolts (not shown in any more detail here) at the upperright hand and lower right hand door region, with these moving into twocorresponding bores inside the door 106 on actuation, which takes placeautomatically. The moving in and out takes place pneumatically. Anerroneous opening of the door 106 on a failure of the pneumatics isprecluded by the bolts moved into the door and by the lateral forcesoccurring by the pressure load of the door. To check whether thelatching has taken place, Hall proximity sensors can be integrated whichdetect the movement of the bolts. In addition, this signal can be linkedto information on the door position which can be picked up by a separatesensor. In addition, the latching bolt not shown in any more detail herecan have a latch connection. This latch connection consists of aspring-loaded latch ball on the door side which latches into acorresponding arch of the latch bolt and can hold the door in thecorresponding position. An introduction slope is provided for thesimplified latching. To open the door from the latch position, the latchball present here is drawn back by means of a mechanical system.

On the side of the fluid treatment machine 100, the blood circuitsubstantially consists of at least one hydraulically controlled membranepump having two independent pump chambers C and D which can be used as ahighly precise flow pump or as a volumetric metering unit, a row ofvalves M, O and clamps N for the control of the flow path, a highlyintegrated sensor system G, H required for monitoring and control, anactive air extractor, i.e., an air separation chamber I with a connectedcassette venting A, of the blood circuit (air-free circuit) and a door106 to fix the cassette 10.

The fluid treatment machine 100 respectively comprises a pneumaticsystem for the overpressure and a pneumatic system for theunderpressure. The underpressure serves, for example, to apply anunderpressure between the foil 14 of the cassette 10 and the unit sideto prevent a passage restriction on the plastic deformation of the foil,to raise the foil at feed positions and thus to be able to keep theaccess free, to avoid air compliance in the pump devices and to be ableto ensure an air-free coupling between the sensor and the foil atspecific sensor positions. The air suction requires openings in the unitside and a suction unit, i.e., a vacuum pump, connected to it, whereinthe vacuum distribution should be ensured as uniformly and as reliablyas possible over the whole surface. In the idling state, the openingsshould be at least largely closed to permit a good cleaning here. Inoperation, however, a problem-free air suction should be possible. Thisproblem is solved by the elastomer mat of the type described above.

In the cassette 10, no passage seals are contained except for the edgeregion and some safety weld connections. The sealing of all flow pathsand passages must therefore take place by pressing. For this purpose,the cassette has sealing beads 52 on the passage rims which have alreadybeen described above and which are sealable on the pressing of thedisposables between the machine block 108 and the door 106 by pressinginto the elastic mat.

The air distributor plate not shown in any more detail here is locatedon the rear side of the machine block 108 and is connected to the, forexample, two membrane pumps of the pneumatic system, namely theoverpressure pump and the underpressure pump. The air distributor plateis sealed with respect to the rear side of the machine block by asealing mat and permits the compressed air and vacuum feed viaintegrated passage structures so that every valve does not need its owntubing. A plurality of circuits are present on the air distributorplate, namely a vacuum circuit, a compressed air circuit which isdirectly connected to the compressor for the supply of components whichalways need compressed air, a compressed air circuit for the protectionof sensitive components which may only be charged with compressed airunder certain states, with it also being separable from the compressorby an on/off valve and an exhaust circuit.

By integration of a plurality of control valves on the air distributorplate, the electrical supply can also be collected via a small controlboard. Since a plurality of valves are only needed with specificoptions, a modular retrofitting capability must be ensured.

The sensor system and the pump connections are guided through the platethrough apertures and cut-outs.

Sensors which are collected in integrated sensor modules in the presentfluid treatment machine 100 are required for the monitoring and controlof the extracorporeal blood circuit. Two respective modules worktogether as a pair. One module is accommodated in the door 106 and thecounter-piece in the machine block 108. Both the arterial branch shouldbe monitored by the arterial measuring chamber G and the venous branchby the venous measuring chamber H. The integrated measurement sensorsystem is described in detail in the German patent applications DE 19837 667 A and DE 101 43 137 of the same patent applicant. The sensorstogether have the following properties or provide the followingpossibilities:

measurement and monitoring of the blood volume;

measurement of the hematocrit;

measurement and monitoring of the thermal energy balance;

measurement and monitoring of the body temperature;

measurement of the conditions of the fistula (with circulation);

air detection;

fistula pressure measurement.

A multi-sensor module is usually fitted with an ultrasonic sensor forvolume monitoring, measurement of the hematocrit and the air detection,with a temperature sensor for the automatic access analysis, bodytemperature monitoring and thermal energy balance, with a pressuresensor for the pressure monitoring and with an optical sensor for theautomatic detection of blood.

The valves M and the pump valves O have a similar design to those valvesdescribed above.

In addition to the aforesaid valves which are shown in FIG. 7, so-calledphantom valves, which are not drawn in any more detail in this FIG. 7,are additionally present. The design and function of the phantom valvesare similar to the design and function of the phantom valves discussedabove.

Reference letter N designates safety clamps which serve to achieve asafe state during an alarm in the extracorporeal blood circuit, withthem interrupting the patient line and thus any blood flow from or tothe patient. To avoid unwanted compliance effects, and since the systemis designed for a flow reversal, this safety function must be ensuredboth on the arterial side and on the venous side so that two blockingclamps N are used which can be mechanically coupled.

The blocking clamps should be effective as close to the patient aspossible in order to be able to minimize any interference and to satisfyhigh safety demands. For this reason, tube clamps are used which actdirectly on the patient tubes.

A possible embodiment, such as is provided here, consists of theclamping of the tubes against a clamping rail on the inner side of thedoor by means of a recloseable pneumatically opened clamping slide. Sucha system is passively spring-closing, namely without pressure andwithout current and so is also advantageous in the case of a failureunder safety aspects.

In FIG. 8, a fluid treatment machine 100 is shown corresponding to FIG.7 with an inserted cassette 10 corresponding to FIG. 2. In FIG. 9, incontrast, a fluid treatment machine 100 is shown with a cassette 10corresponding to the embodiment variant in accordance with FIG. 5, withthe dialyzer in the cassette here having an automatic dialysateconnection K and L to the fluid treatment machine 100.

The new apparatus shown here follows a strictly modular approach whileachieving a high flexibility and deployment possibility also withrespect to future deployment possibilities and options. The integratedblood module permits the carrying out of the whole spectrum of the bloodtreatment procedures, namely standard hemodialysis, onlinehemodiafiltration, online hemofiltration and also acute treatment.

It must be pointed out with respect to the acute treatment that themachines serving the acute treatment, i.e., the acute dialysis or acutefiltration, have to have a simple design in order to be able to betransported corresponding easily and to be able to work without acomplex supply structure (e.g. water connection). In this system,therefore, work is carried out practically without exception with bagswith premanufactured solutions. Using the embodiments shown in FIGS. 3to 6, acute hemofiltration can then be carried out easily in which thesubstituate is supplied from a bag and filtrate is removed from thefilter into an empty bag with the pumps shown.

Except for the connection of the bags, no further measure is necessaryin this case. It would naturally nevertheless be possible toadditionally make a dialysis possible with a corresponding effort.Furthermore, the substituate pump could alternatively be used as adialysate supply pump if the connections inside the cassette werechanged accordingly. Then dialysis fluid filled into bags could besupplied in balanced form to the filter via the membrane pump, whilefluid is led out in a controlled manner via the filtrate pump. Nofurther components would also be necessary for the fluid control in sucha machine.

Each of these types of treatment can take place both in two-needle andin single-needle mode. Reference is made here to the German patent DE100 42 324 C1 with respect to the description of the two-needle orsingle-needle mode.

Other embodiments are within the scope of the following claims.

1. A medical system, comprising: a medical treatment machine defining acassette compartment, the medical treatment machine comprising aplurality of piston pump members and valve members; and a set of medicalfluid cassettes, comprising a first medical fluid cassette configured tobe disposed within the cassette compartment of the medical treatmentmachine, the first medical fluid cassette forming a plurality of fluidchannels and chambers, the medical system being configured to provide afirst type of medical treatment when the first medical fluid cassette isdisposed within the cassette compartment and the plurality of pistonpump members and valve members of the medical treatment machine areoperated in a first manner; and a second medical fluid cassetteconfigured to be disposed within the cassette compartment of the medicaltreatment machine, the second medical fluid cassette forming a pluralityof fluid channels and chambers, the medical system being configured toprovide a second type of medical treatment that is different than thefirst type of medical treatment when the second medical fluid cassetteis disposed within the cassette compartment and the plurality of pistonpump members and valve members of the medical treatment machine areoperated in a second manner that differs from the first manner, whereinthe configuration of the plurality of fluid channels and chambers of thefirst medical fluid cassette is different than the configuration of theplurality of fluid channels and chambers of the second medical fluidcassette, and the medical treatment machine has the same structuralconfiguration when operated with the first medical fluid cassette toprovide the first type of medical treatment as when operated with thesecond medical fluid cassette to provide the second type of medicaltreatment.
 2. The medical system of claim 1, wherein the first cassetteis configured for standard hemodialysis.
 3. The medical system of claim2, wherein the second cassette is configured for onlinehemodiafiltration.
 4. The medical system of claim 1, wherein the set ofmedical fluid cassettes further comprises a third medical fluid cassetteconfigured to be disposed within the cassette compartment of the medicaltreatment machine, the third medical fluid cassette forms a plurality offluid channels and chambers, and the medical system is configured toprovide a third type of medical treatment that is different than thefirst and second types of medical treatments when the third medicalfluid cassette is disposed within the cassette compartment and theplurality of piston pump members and valve members of the medicaltreatment machine are operated in a third manner that differs from thefirst and second manners, and wherein the configuration of the pluralityof fluid channels and chambers of the third medical fluid cassette isdifferent than the configurations of the plurality of fluid channels andchambers of the first and second medical fluid cassettes, and themedical treatment machine has the same structural configuration whenoperated with the third medical fluid cassette to provide the third typeof medical treatment as when operated with the first and second medicalfluid cassettes to provide the first and second types of medicaltreatment, respectively.
 5. The medical system of claim 4, wherein thefirst cassette is configured for standard hemodialysis, the secondcassette is configured for online hemodiafiltration, and the thirdcassette is configured for acute dialysis.
 6. The medical system ofclaim 1, wherein each of the cassettes includes a bar code thereon, andthe medical treatment machine comprises a sensor system configured toidentify the cassettes when the cassettes are disposed within thecassette compartment.
 7. The medical system of claim 1, wherein thefirst and second medical fluid cassettes are configured to beinterchangeably disposed within the cassette compartment of the medicaltreatment machine.
 8. The medical system of claim 1, wherein the medicaltreatment machine is a dialysis machine.
 9. The medical system of claim1, wherein only some of the plurality of piston pump members and valvemembers of the medical treatment machine are operated to provide thefirst type of medical treatment.
 10. The medical system of claim 9,wherein all of the plurality of piston pump members and valve members ofthe medical treatment machine are operated to provide the second type ofmedical treatment.
 11. The medical system of claim 1, wherein at leastone of the first and second medical fluid cassettes comprises a coverfoil that is welded to a base body along an edge region of the basebody, and the at least one of the first and second cassettes comprises aregion that contains substituate and is surrounded by a weld seam.
 12. Aset of medical fluid cassettes, comprising: a first medical fluidcassette forming a plurality of fluid channels and chambers, theplurality of fluid channels and chambers of the first medical fluidcassette being configured so that the first medical fluid cassette canbe used with a medical treatment machine to provide a first type ofmedical treatment; a second medical fluid cassette forming a pluralityof fluid channels and chambers, the plurality of fluid channels andchambers of the second medical fluid cassette being configured so thatthe second medical fluid cassette can be used with the medical treatmentmachine to provide a second type of medical treatment that is differentthan the first type of medical treatment, wherein the configuration ofthe plurality of fluid channels and chambers of the first medical fluidcassette is different than the configuration of the plurality of fluidchannels and chambers of the second medical fluid cassette, and thefirst and second medical fluid cassettes are configured so that themedical treatment machine can have the same structural configurationwhen operated with the first medical fluid cassette to provide the firsttype of medical treatment as when operated with the second medical fluidcassette to provide the second type of medical treatment.
 13. The set ofmedical fluid cassettes of claim 12, wherein the first cassette isconfigured for standard hemodialysis.
 14. The set of medical fluidcassettes of claim 13, wherein the second cassette is configured foronline hemodiafiltration.
 15. The set of medical fluid cassettes ofclaim 12, further comprising a third medical fluid cassette forming aplurality of fluid channels and chambers, the plurality of fluidchannels and chambers of the third medical fluid cassette beingconfigured so that the third medical fluid cassette can be used with themedical treatment machine to provide a third type of medical treatmentthat is different than the first and second types of medical treatment,wherein the configuration of the plurality of fluid channels andchambers of the third medical fluid cassette is different than theconfigurations of the plurality of fluid channels and chambers of thefirst and second medical fluid cassettes, and the third medical fluidcassette is configured so that the medical treatment machine can havethe same structural configuration when operated with the third medicalfluid cassette to provide the third type of medical treatment as whenoperated with the first and second medical fluid cassettes to providethe first and second types of medical treatment, respectively.
 16. Theset of medical fluid cassettes of claim 15, wherein the first cassetteis configured for standard hemodialysis, the second cassette isconfigured for online hemodiafiltration, and the third cassette isconfigured for acute dialysis.
 17. The set of medical fluid cassettes ofclaim 12, wherein each of the cassettes includes a bar code thereon toidentify the cassette.
 18. The set of medical fluid cassettes of claim12, wherein the first and second medical fluid cassettes are configuredto be interchangeably disposed within a cassette compartment of themedical treatment machine.
 19. The set of medical fluid cassettes ofclaim 12, wherein at least one of the first and second medical fluidcassettes comprises a cover foil that is welded to a base body along anedge region of the base body, and the at least one of the first andsecond cassettes comprises a region that contains substituate and issurrounded by a weld seam.